FIG. 1 illustrates a known device for modulating light, described in U.S. Patent Application Publication No. 2002047564 filed on behalf of LG PHILIPS LCD Co LTD.
There is shown a modulating structure which is located on a silicon substrate 11 on which is arranged a first set of opaque masks 12 separated by windows letting the light in. Shutters 13 having different sizes may be individually controlled so as to close one, two or more shutters and than mask and modulate the light lighting an optical sensor located under the shutters. The shutters are operated by means of a so-called PULL-IN voltage causing the application of an electrostatic force. Beyond one given threshold, the electrostatic force results a beam to be bent and stick on the surface of the silicon substrate, entailing an effect of modulation of the light going to the sensitive part of the optical sensor. In this first system known in the art, each shutter works in an ON/OFF state and the modulation of the light is achieved by means of one control of the addressing of the different shutters. Generally speaking, this first known device is particularly difficult to manufacture.
FIG. 2 illustrates a second known device which achieves the modulation of the light by means of the activation of a shutter 23 which moves in an horizontal direction and can mask all or part of a window letting the light in and go to the surface of a substrate 21 including optical sensors 22.
The devices which were mentioned above do not achieve the realization of an integrated modulator sensor, thus requiring the combination of a known sensor to the known modulators. This entails waste of space on the integrated circuit.